From cf10c476b8dbe718f05da15a705ba106eae9f621 Mon Sep 17 00:00:00 2001

From: "C. Masloch"  <pushbx@38.de>

Date: Sun, 27 Jan 2013 16:07:25 +0100

Subject: [PATCH 141/364] 	Improve FreeDOS direct loading support

 compatibility.

	* include/grub/i386/relocator.h (grub_relocator16_state):

	New member ebp.

	* grub-core/lib/i386/relocator.c (grub_relocator16_ebp): New extern

	variable.

	(grub_relocator16_boot): Handle %ebp.

	* grub-core/lib/i386/relocator16.S: Likewise.

	* grub-core/loader/i386/pc/freedos.c:

	Load BPB to pass kernel which partition to load from.

	Check that kernel file is not too large.

	Set register dl to BIOS unit number as well.

---

 ChangeLog                          | 15 ++++++++++

 grub-core/lib/i386/relocator.c     |  2 ++

 grub-core/lib/i386/relocator16.S   |  5 ++++

 grub-core/loader/i386/pc/freedos.c | 61 ++++++++++++++++++++++++++++++++++----

 include/grub/i386/relocator.h      |  1 +

 5 files changed, 79 insertions(+), 5 deletions(-)

diff --git a/ChangeLog b/ChangeLog

index 8c4d087..f5cb7dc 100644

--- a/ChangeLog

+++ b/ChangeLog

@@ -1,3 +1,18 @@

+2013-01-27  C. Masloch  <pushbx@38.de>

+

+	Improve FreeDOS direct loading support compatibility.

+

+	* include/grub/i386/relocator.h (grub_relocator16_state):

+	New member ebp.

+	* grub-core/lib/i386/relocator.c (grub_relocator16_ebp): New extern

+	variable.

+	(grub_relocator16_boot): Handle %ebp.

+	* grub-core/lib/i386/relocator16.S: Likewise.

+	* grub-core/loader/i386/pc/freedos.c:

+	Load BPB to pass kernel which partition to load from.

+	Check that kernel file is not too large.

+	Set register dl to BIOS unit number as well.

+

 2013-01-22  Colin Watson  <cjwatson@ubuntu.com>

 	* util/grub-reboot.in (usage): Document the need for

diff --git a/grub-core/lib/i386/relocator.c b/grub-core/lib/i386/relocator.c

index df25b30..0170eed 100644

--- a/grub-core/lib/i386/relocator.c

+++ b/grub-core/lib/i386/relocator.c

@@ -54,6 +54,7 @@ extern grub_uint16_t grub_relocator16_sp;

 extern grub_uint32_t grub_relocator16_edx;

 extern grub_uint32_t grub_relocator16_ebx;

 extern grub_uint32_t grub_relocator16_esi;

+extern grub_uint32_t grub_relocator16_ebp;

 extern grub_uint16_t grub_relocator16_keep_a20_enabled;

@@ -225,6 +226,7 @@ grub_relocator16_boot (struct grub_relocator *rel,

   grub_relocator16_ss = state.ss;

   grub_relocator16_sp = state.sp;

+  grub_relocator16_ebp = state.ebp;

   grub_relocator16_ebx = state.ebx;

   grub_relocator16_edx = state.edx;

   grub_relocator16_esi = state.esi;

diff --git a/grub-core/lib/i386/relocator16.S b/grub-core/lib/i386/relocator16.S

index e79d875..c8d6f86 100644

--- a/grub-core/lib/i386/relocator16.S

+++ b/grub-core/lib/i386/relocator16.S

@@ -259,6 +259,11 @@ VARIABLE(grub_relocator16_edx)

 VARIABLE(grub_relocator16_ebx)

 	.long	0

+	/* movl imm32, %ebp.  */

+	.byte	0x66, 0xbd

+VARIABLE(grub_relocator16_ebp)

+	.long	0

+

 	/* Cleared direction flag is of no problem with any current

 	   payload and makes this implementation easier.  */

 	cld

diff --git a/grub-core/loader/i386/pc/freedos.c b/grub-core/loader/i386/pc/freedos.c

index f1eed57..e685c6e 100644

--- a/grub-core/loader/i386/pc/freedos.c

+++ b/grub-core/loader/i386/pc/freedos.c

@@ -32,6 +32,7 @@

 #include <grub/video.h>

 #include <grub/mm.h>

 #include <grub/cpu/relocator.h>

+#include <grub/machine/chainloader.h>

 GRUB_MOD_LICENSE ("GPLv3+");

@@ -40,8 +41,23 @@ static struct grub_relocator *rel;

 static grub_uint32_t ebx = 0xffffffff;

 #define GRUB_FREEDOS_SEGMENT         0x60

+#define GRUB_FREEDOS_ADDR            (GRUB_FREEDOS_SEGMENT << 4)

 #define GRUB_FREEDOS_STACK_SEGMENT         0x1fe0

-#define GRUB_FREEDOS_STACK_POINTER         0x8000

+#define GRUB_FREEDOS_STACK_BPB_POINTER     0x7c00

+#define GRUB_FREEDOS_BPB_ADDR        ((GRUB_FREEDOS_STACK_SEGMENT << 4) \

+                                       + GRUB_FREEDOS_STACK_BPB_POINTER)

+

+/* FreeDOS boot.asm passes register sp as exactly this. Importantly,

+   it must point below the BPB (to avoid overwriting any of it). */

+#define GRUB_FREEDOS_STACK_POINTER         (GRUB_FREEDOS_STACK_BPB_POINTER \

+                                             - 0x60)

+

+/* In this, the additional 8192 bytes are the stack reservation; the

+   remaining parts trivially give the maximum allowed size. */

+#define GRUB_FREEDOS_MAX_SIZE        ((GRUB_FREEDOS_STACK_SEGMENT << 4) \

+                                       + GRUB_FREEDOS_STACK_POINTER \

+                                       - GRUB_FREEDOS_ADDR \

+                                       - 8192)

 static grub_err_t

 grub_freedos_boot (void)

@@ -49,14 +65,16 @@ grub_freedos_boot (void)

   struct grub_relocator16_state state = { 

     .cs = GRUB_FREEDOS_SEGMENT,

     .ip = 0,

-    .ds = 0,

+

+    .ds = GRUB_FREEDOS_STACK_SEGMENT,

     .es = 0,

     .fs = 0,

     .gs = 0,

     .ss = GRUB_FREEDOS_STACK_SEGMENT,

     .sp = GRUB_FREEDOS_STACK_POINTER,

+    .ebp = GRUB_FREEDOS_STACK_BPB_POINTER,

     .ebx = ebx,

-    .edx = 0,

+    .edx = ebx,

     .a20 = 1

   };

   grub_video_set_mode ("text", 0, 0);

@@ -79,8 +97,9 @@ grub_cmd_freedos (grub_command_t cmd __attribute__ ((unused)),

 {

   grub_file_t file = 0;

   grub_err_t err;

-  void *kernelsys;

+  void *bs, *kernelsys;

   grub_size_t kernelsyssize;

+  grub_device_t dev;

   if (argc == 0)

     return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));

@@ -95,12 +114,44 @@ grub_cmd_freedos (grub_command_t cmd __attribute__ ((unused)),

   if (! file)

     goto fail;

+  {

+    grub_relocator_chunk_t ch;

+    err = grub_relocator_alloc_chunk_addr (rel, &ch, GRUB_FREEDOS_BPB_ADDR,

+					   GRUB_DISK_SECTOR_SIZE);

+    if (err)

+      goto fail;

+    bs = get_virtual_current_address (ch);

+  }

+

   ebx = grub_get_root_biosnumber ();

+  dev = grub_device_open (0);

+

+  if (dev && dev->disk)

+    {

+      err = grub_disk_read (dev->disk, 0, 0, GRUB_DISK_SECTOR_SIZE, bs);

+      if (err)

+	{

+	  grub_device_close (dev);

+	  goto fail;

+	}

+      grub_chainloader_patch_bpb (bs, dev, ebx);

+    }

+

+  if (dev)

+    grub_device_close (dev);

   kernelsyssize = grub_file_size (file);

+

+  if (kernelsyssize > GRUB_FREEDOS_MAX_SIZE)

+    {

+      grub_error (GRUB_ERR_BAD_OS,

+		  N_("file `%s' is too large"), argv[0]);

+      goto fail;

+    }

+

   {

     grub_relocator_chunk_t ch;

-    err = grub_relocator_alloc_chunk_addr (rel, &ch, GRUB_FREEDOS_SEGMENT << 4,

+    err = grub_relocator_alloc_chunk_addr (rel, &ch, GRUB_FREEDOS_ADDR,

 					   kernelsyssize);

     if (err)

       goto fail;

diff --git a/include/grub/i386/relocator.h b/include/grub/i386/relocator.h

index 46becb8..5f89a7e 100644

--- a/include/grub/i386/relocator.h

+++ b/include/grub/i386/relocator.h

@@ -49,6 +49,7 @@ struct grub_relocator16_state

   grub_uint32_t ebx;

   grub_uint32_t edx;

   grub_uint32_t esi;

+  grub_uint32_t ebp;

   int a20;

 };

-- 

1.8.1.4